In recent years, electronics has come to be dominated by semiconductor devices, which are found in the discrete devices and integrated circuits of computers, calculators, televisions, VCRs, radios, telephones, answering machines, wristwatches, cameras, and cars, among others. Semiconductor devices are formed from semiconductors, which are compounds having conductivities intermediate between those of the high-conductivity conductors and the low-conductivity insulators. Here, conductivity refers to a compound's ability to conduct electricity; compounds with greater conductivities are able to conduct greater amounts of electricity.
Semiconductors are important in part because their conductivity readily may be altered by the addition of certain foreign compounds. These foreign compounds are known as dopants, and the addition of these foreign compounds to semiconductors is known as doping.
Doping may be used to create two types of semiconductors: n-type semiconductors and p-type semiconductors. In n-type semiconductors, the dopant adds negative charge carriers, which typically comprise extra electrons. Examples of n-type dopants for silicon-based semiconductors include phosphorus (P), arsenic (As), and antimony (Sb). In p-type semiconductors, the dopant adds positive charge carriers, which typically comprise holes (or missing electrons). Examples of p-type dopants for silicon-based semiconductors include boron (B).
Although doping is essential to semiconductor technology, current doping methods suffer from a number of shortcomings. In particular, current doping methods involve doping monocrystalline semiconductors as they are produced from polycrystalline precursors. Doping monocrystalline semiconductors may involve frequent storing, weighing, and handling of dopant. This processing requires special equipment, which may be bulky and expensive. This processing also requires an operator, which may expose the operator to extremely toxic dopants, such as arsenic. Doping monocrystalline semiconductors also may involve loss or uneven distribution of dopant.